A former Chinese cabinet minister was sentenced to life in prison yesterday in a high-level bribery case that has exposed rampant corruption in the country's profit-oriented dictatorship.

Amid leadership fears that endemic corruption is undermining the legitimacy of the Communist party, a Beijing court convicted Tian Fengshan, who was fired as minister of land and resources in 2003, of accepting bribes of 4.4m yuan ($545,000).

The highest level bribery trial in four years was hailed by the state-controlled media as a sign that the authorities were cracking down on influence-peddling and illegal land transfers, which are increasingly the target of violent protests.

But Tian was spared the death penalty. The court said it had been "lenient" because the defendant had confessed and helped police recover illegally obtained assets. Tens of thousands of communist cadres have been sacked, fined, imprisoned or executed for corruption in recent years, but it is rare for such a senior figure to be implicated.

Before Tian joined the cabinet, he was governor of Heilongjiang, a province bigger than many countries with a population of more than 38 million people. From 1995 to 2000, he oversaw a system oiled by bribery. For the right sum, he dispensed official positions, organised funding for projects and helped to reclassify farmland so that it could be taken over by developers.

Although he was found guilty on 17 charges of bribery involving half a million dollars, his position and reputation suggest this may have been the tip of the iceberg. Several years before his arrest, Tian was the thinly veiled subject of a best-selling novel about corruption in Heilongjiang, The Snow Leaves No Trace.

He came under police scrutiny when a Communist party associate, Ma De, admitted paying him 100,000 yuan in 1999 for helping to arrange financing for a broadcasting facility.

In a sign of systematic influence-peddling, Ma said that he had paid 800,000 yuan for his post as a local party secretary. After getting the job, he then sold other positions for 24m yuan.

As the case widened, it decimated the top level of the Heilongjiang administration. Among those fired or jailed were the president of the high court, the top prosecutor, the vice-governor, the deputy head of the legislature and at least 10 mayors and vice-mayors. Ma and another associate, Han Guizhi, have been given suspended death sentences, which are often commuted to life in prison.

Zhu Shengwen, a former deputy mayor of Harbin, reportedly committed suicide in jail. The official version of his death is that he threw himself out of a prison window. His family say he was killed to prevent him from exposing further cases of embezzlement.

Since taking power almost three years ago, President Hu Jintao and the prime minister, Wen Jiabao, have tried to dispel growing public cynicism about "crony communism" by purging the ruling party of those found guilty of corruption and ordering the entire membership to undergo re-education.

According to the party's anti-corruption watchdog, the central commission for discipline inspection, nearly 50,000 officials have been prosecuted and punished in the past two years. More than 1,000 cadres have committed suicide and 8,000 fled overseas. But the top-down approach of "strengthening party discipline" is systematically undermined by political patronage and a lack of media scrutiny and electoral accountability. He Yong, deputy secretary of the commission, recently said the number of corruption cases was declining, but those involving senior officials was on the increase.